Dropout fuse for high voltage electric power circuits



Au 16,1966 H, J, BART; 3,267,235

DROPOUT .FUSE FOR HIGH VOLTAGE ELECTRIC POWER CIRCUITS Filed Oct. :64, 1962 s Sheets-Sheet 1 I I I II I' I $331 1 I I I 164 M I L 134 163 1J4 10 107 133 111 106 "11 g l I I 6. |NSULATION\ I ,J.

l I l. #4- l l I I l l I I I I 2 I I I l I I INVENTOR. HENRY .J. BARTA DROPOUT FUSE FOR HIGH VOLTAGE ELECTRIC POWER CIRCUITS Filed Odt. 24, 1962 H. J. BARTA 5 Sheets-Sheet 2 74VI l/ l/ll/l/Il/l/li71/6FIAFI/l/l/l/A H. J. BART'A 3,

DROPOUT FUSE FOR HIGH VOLTAGE ELECTRIC POWER CIRCUITS Aug. 16, 1966 5 Sheets-$heet 3 Filed Oct. 24

NHWI WHIW :1 u. t HU m Aux I L LIL lllll II T PI 9 5 INSULATING PLATE HAVING 67 A COATING OF HIGH RESISTANCE CONDUCTING 1'; MATERIAL. -=i-.

H. J. BARTA DROPOUT FUSE FOR HIGH VOLTAGE ELECTRIC POWER CIRCUITS Filed Oct. 24. 1962 5 Sheets-Sheet 4 H. J. BARTA DROPOUT FUSE FOR HIGH VOLTAGE ELECTRIC POWER CI RCUITS Filed on. 24. 1962 5 Sheets-Sheet 5 III'IIIIlIl-lvlll'allll'lll' IlllllllllllllI-IIIIOIIIIIII Ill This invention relates, generally, to circuit interrupters and it has particular relation to the mounting of dropout fusesfor use on alternating current transmission circuits operating at voltages of the order of 34.5 kv. and above. It constitutes an improvement over the constructions shown in US. Patent No. 2,578,255, issued December 11,

1951, to S. I. Lindell and in US. Patent No. 2,750,469,

issued June 12, 1956, to C. H. Baker. The dropout fuse' construction is disclosed in copending application Serial No. 227,335, filed October l, 1962, in the name of H. H. Fahnoe and assigned to the assignee of this application.

Among the objects of this invention are: To provide for mounting a fuse, such as a dropout fuse, in anew and improved manner on metallic support bases that are positioned in insulated spaced relation one above-the nited States Patent other; to construct a power fuse for operation at the voltages above mentionedwhich can be manipulated by a lineman with the ease and facility to which he is accustomed for relatively low voltage distribution type dropout fuses with the same live line tool equipment that is employed for such fuses and is ordinarily available in substations and on linemens trucks; to provide such a construction for power fuses which can be inserted on the hinge terminal and operated by a lineman on apole or from a position on the ground using a live line tool having a correspondingly long insulating handle; to construct the support bases, trunnion assembly and fuse tube release assembly principally or entirely of relatively inex-.

pensive light weight, corrosion resisting metal, such as aluminum or magnesium or alloys thereof, or of plastic insulating material and to provide relatively low electrical resistance connecting means between terminal pads of cop-. per or copper alloy on the support bases and the respective fuse tube terminal; to nullify the capacity effect be tween an energized hinge terminal pad and its metallic support base by providing a high resistance conducting path therebetween inorder to reduce radio interference .resulting therefrom; to construct the end fittings for the fuse tube of material having the same electrical and mechanical characteristics as the support bases with special provision being made for direct electrical connections between the fuse tube terminals and means providing connections to the respective terminal pads; to provide a latch that functions to hold a dropout fuse of the power type in latched position promptly upon its being swung to. this position, permits the device being slammed to closed position and does not require relatively slow closing motion to insure proper latching; to provide a construction for a dropout power fuse that permits closing on a load or a fault without causing such arcing that difficulty would be encountered due to arcing to'an adjacent phase or ground; to avoid the necessity of providing a disconnecting switch in the circuit to isolate the dropout 'fuse; to reduce thefriction forces and provide a me- 'ice Patented August 16, 1966 FIG. 2 is a view, in side elevation, of a dropout fuse provided with trunnion and fuse tube release assemblies arranged for cooperating with the hinge and latch assemblies of the mounting shown in FIG. 1.

FIGS. 3A and 3B, with the former placed above the latter, show a vertical longitudinal cross sectional view of the dropout fuse shown in FIG. 2, the showing here being at an enlarged scale.

FIG. 4 is a top planview of the hinge assembly, the

showing being at an enlarged scale.

FIG. 5 is a view, in side elevation, of the hinge assembly shown in FIG. 4.

FIG. 5A is a view, in front elevation, of an insulating plate that is interposed in the hinge assembly shown in FIG. 6 is a view, in side elevation, of a trunnion assembly for mounting on the lower end of the fuse tube as shown in FIG. 2, the showing here being at an enlarged scale.

FIG. 7- is a top plan view of the trunnion assembly shown in FIG. 6 with a sectional view taken through the fuse tube generally along the line 77 of FIG. 2.

FIG. 8 is a top plan view, at an enlarged scale, of the latch assembly that is mounted on the upper insulator of the mounting shown in FIG. -1.

FIG. 9 is'a vertical sectional view, taken generally along the line 9-9 of FIG. 8.

FIG. 10 is a detail sectional view,at an enlarged scale, taken generally along the line 10-10 of FIG. 8.

FIG. 11 is a view, partly in side elevation and partly in vertical section, showing at an enlarged scale the details of construction of the fuse tube release assembly that is mounted on the upper end of the fuse tube shown in FIG. 2.

FIG. 12 is a horizontal sectional view at an enlarged scale taken generally along the line 12--12 of FIG. 11. Referring now particularly to FIG. 1 of the drawings, it will be observed that the reference character 10 designates, generally, a mounting for a circuit interrupter of the dropout fuse type. The mounting 10 includes a channel base 11 which carries a lower insulator 12 and an upper insulator 13 in parallel spaced laterally extending relation. A hinge assembly, shown generally at 14, is mounted on the distal end of the lower insulator 12. FIGS. 4 and 5 show the details of construction. The distal end of the upper insulator 13 carries a latch assembly that is indicated, generally, at 15 and FIGS. 8, 9 and 10 show the details of construction thereof.

In FIG. 2 there is shown, generally, at 1 6 a dropout fuse which includes a fuse tube 17 the internal details of construction of which are shown in FIGS. 3A and 3B. At its lower end the fuse tube 17 has a trunnion assembly that is indicated, generally, at 18 with the details of construction being shown in FIGS. 6 and 7 of the drawings. At its upper end the fuse tube 17 carnies a fuse tube release assembly that is indicated, generally, at

' 19 and its details of construction are shown in FIGS. 11

and 12.

As indicated, the detailsof construction of the dropout fuse 16 are shown in FIGS. 3A and 3B. 'Here it will be observed that the lower end of the fuse tube 17 is provided with a lower terminal or ferrule 22 having an annular groove 23. At its upper end the fuse 17 is provided with an upper terminal 24 in the form of a tube of good conducting material such as copper. The upper tubular terminal 24 extendsupwardly from inside of the fuse tube 17 and its upper end 25 is turned over a washer 26 having a central opening 27. The opening 27 is provided to permit movement therethrough of a latch trip pin 28 which, as described hereinafter, functions to release the dropout fuse 16 from the latch assembly 15 and permits it to swing downwardly to open position on the hinge assembly 14.

The latch trip pin 28 extends upwardly from a rod like terminal 29 which is provided at its upper-end with a rod end fitting30 having a downwardly facing shoulder 31 against which the upper end of a coil compression spring 32 reacts. The lower end of the coil compression 35 to thelowerend of a contact sleeve36 which has contact fingers 37 at its upper end that are biased-by a garter spring 38 into contact engagement with a contact section 39 on the rod like terminal 29. This construction provides alow resistance path for the current flow from the upper tubular terminal 24 to the rod like terminal 29 under normal operating conditions while the dropout fuse 16 is carrying normal load current. When the rod like terminal 29 is released, as described hereinafter, the contact fingers 37 no longer make contact with the surface of the contact section 39 but make contact with the portion of the rod like terminal 29 therebelow as it moves formed of high strength material such a's'a nickel chro-' mium alloy. The lower end of the terminal rod 41 is anchored to a transversely extending bridge 44 by nuts 45. The bridge 44 is secured at its ends to an inner met-a1- lic sleeve 46 which extends upwardly from the lower end of the fuse tube 17. Its lower end 47 is secured by rivets 48 to the lower end of the lower terminal or ferrule 22. A closure disc 49 extends across the lower end of the outfiared lower end of the inner metallic sleeve 46 to prevent the entrance of insects and the like from the exhaust lower end of the fuse tube 17.

The rod like terminal 29 extends downwardy through acup shaped end washer 50 and through a bore 51 that is formed in a stack of cakes 52 of arc extenguishing material from which an arcextinguishing medium is evolved due to the heat of the arc. The cakes 52 can be formed of boric acid or a combination of this material and other arc extinguishing materials as described in the application of H. H. Fahnoe and abovereferred to. The lowermost cake 52 of arc extinguishing material is provided with a conical throat 53 and a fiber plug 54 is positioned therebelow and at the upper end of the inner metallic sleeve 46. The interior of the fiber plug 54 defines an arcing chamber 55 in which the major portionof the fusible element 40 is located. It will be understood that the space shown between the inner surface of the fuse tube 17 and the outer surfaces of the upper tubular terminal 24, the cakes 52 of arc extinguishing material, the fiber plug 54 and the inner metallic sleeve 45 is filled with a suitable cement, such as an epoxy cement.

Referring now particularly to FIGS. 4 and of the drawings, it will be observed that the reference character 58 designates, generally, a metallic hinge base which forms a part of the hinge assembly 14. Preferably the metallic hinge base 58 is formed of a metal such as cast aluminum or magnesium alloy in order to provide a light weight, high strength and relatively inexpensive construction. The hinge base 58 includes a base section 59 which is provided with bolt holes 60-60 for receiving mounting bolts one ofwhich is indicated at 61 in FIG. 1 to 70 were applied directly to the boss 68, it would pro- 'rnount it on the lower insulator 12. The-hinge base 58 includes forwardly extending sides 62--62 having trunnion receiving slots 63--63 at their distal ends. Associated with the trunnion slots 63--63 are arcuate flanges 64-64 for cooperation with arcuate shoulders on the trunnion section of thetrunnion assembly 18 which will be described hereinafter. The hinge base 58 has a depending socket 66 on the underside in which a rubber bumper 67 is mounted for absorbing theshock incident to the swinging of the dropout fuse. 16 to the open position.

It is desirable to avoid using the metallic hinge base 58 to conduct current flow from a line conductor or to transfer current from it to another conducting part. Ac-

cordingly, the hinge base 58 is provided with an integral forwardly extending rectangular boss 68 on which a shank 69 of a hinge terminal pad, indicated generally at 70, is mounted. Preferably the hinge terminal pad 70 is formed of copper or copper alloy casting. The hinge terminal pad 70 includes a pad portion 71 provided with apertures 7272 for receiving bolts which serve to clamp a line conductor to the hinge terminal pad 70.

A conducting path between the hinge terminal pad 70 and the associated trunnion assembly 18, FIG. 2, is provided by a hinge contact spring that is indicated, generally, at 73 and is formed of good conducting material, such as beryllium copper, which has the required degree of resiliency as well as'capability of conducting current. The hingecontact spring 73 includes C-shaped end section's 7474 having a fiat common section 75 with the distal ends 7676 in spaced relation for engagement with a trunnion contact plate of the trunnion assembly 18 to be described.

Although the metallic hinge base 58, when of metal, is constructed of relatively good electrical conducting material, such as aluminum, an oxide coating forms over its surface. If the shank 69 of the hinge terminal pad vide an alternate path for current flow particularly under overload and short circuit conditions. Due to the surface resistivity of the boss 68 under these conditions sparking would be likely to occur between trunnions (to be described) and the trunnion slots 63-63 to such an extent that the juxtaposed metallic surfaces would be welded together and prevent dropping out of the fuse tube 17 on release of-the latch assembly 15. The flow of current sufficient to cause such welding of the juxta posed trunnion surfaces is prevented through the provision of an insulating plate 77 between the juxtaposed surfaces of the boss 68 and the shank 690i the hinge terminal pad 70. Clamp bolts 78-78 extend through the assembly with insulating washers 79--79 being located underneath the clamp nuts on the clamp bolts When the dropout fuse 17 is in the open position and the circuit connected to the pad portion 71 of the hinge terminal'pad 70 remains energized, radio interference is I likely to develop when the hinge base 58is completely insulated from the hinge terminal pad 70. To take care of this situation the insulating plate 77 is coated with a high resistance material as seen at 77 in FIG. 5A. The

high resistance material 77' is graphite or the like having a resistance of many thousands of ohms but having sufficient conductivity to carry current of a few microampcres and nullify the capacitance effect resulting from the metallic hinge base 58 being otherwise completely insulated from the hinge terminal, pad 70.

FIGS. 6 and 7 show the details of construction of the trunnion assembly 18 which cooperates with the hinge assembly 14 for pivotally mounting the dropout fuse 16 thereon. It will be noted that the trunnion assembly 18 includes a tubular section 80 that is preferably formed of the same material as the hinge base 58, Le, cast aluminum; The. tubular section 80 is arranged to telescope over the lower terminal or ferrule 22 at the lower end of the fuse tube 17 and it is provided with slots 81-81 on the inner side for receiving the heads of the rivets 48. The tubular section 80 has rearwardly extending walls 82-82 that are joined by an end wall 83 with these walls being formed integrally with a trunnion section 84 having oppositely extending trunnions 85-85 for mounting inthe trunnion receiving slots 63-63 in the forwardly extending sides 62-62 of the hinge base 58. Arcuate shoulders 86-86 are associated with the tnmnions '85-85 for pooperation with the arcuate flanges,

64-64 for the purpose of preventing dislodgement of the trunnions 85-85 from the slots 63-63 after the dropout fuse 16 is swung from the full open position toward the closed position and also during the time that it is being swung from the closed position to the open position. In addition, the cooperation between the flanges 64-64 and shoulders 86-86 is such as to limit the extent of upward movement of the fuse tube 17 when the fusible element '40 blows. I

Also formed integrally with the tubular section 80 and trunnion section 84 is an eye section 87 that is provided for receiving the prong of a switch stick which permits the application and removal of the dropout fuse 16 to and from the hinge assembly 14.

With a view to providing a low electrical resistance conducting path from the hinge contact spring 73 'to'the lower terminal or ferrule 22 at the lower end of the fuse tube 17 a trunnion contact plate 88 is employed. It is formed of good conducting metal such as copper or a copper alloy casting. It extends through an arcuateslot 89 in the upper end of the tubular section 80 and into the annular groove 23 in the lower terminal or ferrule 22.

- Here the arcuate end surface 90 of the trunnion contact the bolt 92 is rotatably mounted in the depending flange 91 and its outer end is headed over so that, depending upon the directionof rotation of the bolt 92, the trunnion contact plate 88 is moved toward or away from the bottom of the groove 23. The bolt 92 is threaded at 94 in the end wall 83.

The end 95 of the trunnion contact plate 88 opposite the arcuate end 90 is flared out and it carries transverse flanges 96-96 having flat contact surfaces 97-97 that are arranged, as shown in FIG. 4, to have contact engagement with the distal ends 76-76 of the hinge contact spring 73. It will be understood that, when the dropout fuse 16 is swung to the closed position, the contact surfaces 97-97 engage the distal ends 76-76 of the /hinge contact spring 73 under substantial contact pressure since these ends are moved inwardly as a result of the movement of the dropout fuse 16 to the closed position to stress the C -shaped end sections 74-74. A nose portion 98 is provided on the trunnion contact plate 88 between the transverse'fianges 96-96 and it has inclined side's 99-99 for entering between the distal ends.

76-76 of the hinge contact spring 73 and spreading them apart when the dropout fuse 16 is swung to the closed position. It will be understood that the trunnions 85-85, which are integral with the trunnion section 84 that extends from the tubular section 80, are formed of the same material as the forwardly extending sides 62-62'of the hinge base 58. When the trunnions 85-85 are inserted in the slots 63-63, there is no likelihood of electrolytic corrosion taking place because the materials are the same, i.e., cast aluminum alloy.

FIGS. 8, 9 and show the details of construction of the latch assembly 15. Here it will be observed that the reference character 102 designates, generally, a metallic latch base that is formred of the .same material as the metallic hinge base 58, i.e., cast aluminum. The

latch base 102 includes a base section 103 that is pro-- vided with bolt holes 104-104 for receiving bolts one of which is indicated at 105 in FIG. 1 for mounting the latch assembly 15 at the distal end of the upper insulator 13.= The latch base 102 includes an integral for-v wardly extending section 106 having an upstanding central web 107. A latch, shown generally at 108, is pivoted at 109 on a hub 110 that is located at the upper end of an arm 111 which extends upwardly from the web 107. The latch 108 is biased downwardly by a coil tension spring 112 one end of which is anchored at 113 to the arm 111 while the other end is anchored to a lug 114 119 a short arm 120 of an L-shaped bracket 121 extends.

The L-shaped bracket 121 is formed of corrosion resisting material such as stainless steel. Its long arm 122 overlies the offset section 118 of the top wall 117 and is secured thereto by rivets 123. The short arm extends along the inner side of a transverse flange 124 that forms an integral part of the latch 108 and extends be tween the side walls 116-116.

As shown more clearly in FIG. 10 the short arm 120 4 forms one side of a relatively wide slot 125 the other side of which is formed by a long section 126 of an L- shaped wall 127 that is formed integrally with the respective side wall 116. A short section 128 of the wall 127 forms the bottom of the slot 125. It will be understood that a relatively wide slot 125 is provided on the inner side of each of the side walls 116. These slots'are provided for loosely receiving trunnions 129- 129 of a non-fixed pivot roller 130 that is formed, preferably of stainless steel; As will appear hereinafter the roller 130 forms a part of the latching connection between the latch 108 and the fuse tube release assembly 19 at the upper end of the dropout fuse 16. Since the trunnions 129-129 are loosely mounted in the relatively wide slots, the action of the roller 130 is unlikely to be interfered with by corrosion or lack of lubrication as would likely be the case if the trunnions 129-129 were mounted in fixed hearings on the latch 108. A two to one mechanical advantage in unlatching is obtained through the use of the roller 130 mounted in the manner described. By loosely mounting the trunnions 129- 129 in the relatively wide slots 125 the non-fixed pivot roller 130 is permitted a. substantial degree of rotary and translatory movement and, since it is held captive by the sides and top and bottoms of each of the slots 125, it is referred to as a non-fixed pivot construction. It will be understood that, in the latched position of the dropout fuse 16, the body of the roller 130 bears against the inner surface 120' of the short arm 120 of the L shaped bracket 121 and thus transmits thereto the forces acting on the dropout fuse 16 tending to rotate it to the open position. It will be noted that the diameter of the body of the roller 130 is such that it cannot escape in the space between the lower end of the short arm 120 and the outer end of the short section 128 of the L-shaped wall 127. The assembly is made by placing the roller 130 in position in the slot 125 and then applying the L-shapedbracket 121 and securing it in place by the rivets 123.

The forwardly extending section 106 is provided with spaced downwardly extending transverse walls 133-133 at its distal end for receiving laterally extending outwardly flaring arcing horns 134-134. They cooperate with the fuse tube release assembly 19, when the dropout fuse 16 swings to the open position or is swung to the closed position, for protecting the latch assembly 15 from direct impingement of an are drawn incident to such action. They also act as guides for the dropout fuse 16 in closing.

The latch base 102 is provided with a transverse wall 136 near its forward end for receiving a shank 137 of a latch terminal pad that is indicated, generally, at 138 and is formed of low electrical resistance material such as copper or a copper alloy casting. It includes a pad por tion 139 provided with apertures one of which is shown at 140 for receiving clamp bolts for the purpose of clamping a line conductor thereto using conventional clamp means. Connection to the shank 137 of the latch terminal pad 138 is provided through a latch contact spring that is indicated, generally, at 141 and preferably comprises two C-shaped end sections 142142 that are formed of good conducting material such as beryllium copper which also is highly resilient. Flat common sections 143143 of the C-shaped end sections 142--142 are dovetailed together and overlie the shank 137. The distal reverse curved ends 144--144 of the C- shaped end sections 142-442 provide for contact engagement with the upper tubular terminal 24 at the upper end of the dropout fuse 16 in a manner to be described presently.

Additional reinforcing action for the latch contact spring 141 can be provided by a C-shaped spring 145 of beryllium copper which is interposed between the latchcontact spring 141 and the shank .137 of the terminal pad 138. Clamp bolts 147 extend through the fiat common sections 143-143 of the C-shaped end sections'142-142 and also through the C-shaped spring 145 for'the purpose of clamping the assembly to the transverse wall 146.

FIGS. 11 and, 12 show the details of construction of the fuse tube release assembly 19 that is mounted on the upper end ofthe fuse tube 17. Here it will be observed that the reference character 151 designates, generally, a sleeve that is formed of relatively high. strength light weight material such as cast aluminum or magnesium alloy. The sleeve 151 has a lower end section 152 that is telescoped over the upper end of the fuse tube 17. It extends in overlying relation to an annular groove 153, FIGS. 3A and 12, near the upper end of the fuse tube 17.

As shown more clearly in FIG. 12 the lower end section 152 of the sleeve 151 has rearwardly extending walls 154-154 interconnected by a wall 155 in which a bolt 156 is threaded. At its forward or inner end the bolt 156 carries a clamp member 157 that is rotatably mounted thereon with the end of the bolt 156 being headed over as indicated at 158 to retain the clamp member 157 on the bolt 156. As here shown, when the lower end section 152 is telescopedover the upper end of the fuse tube 17 to such a position that the clamp member 157 registers with the annular groove 153, the bolt 156 can be tightened to move the forward edges of the clamp member 157 into engagement with the bottom surface of the groove 153. In this manner the fuse tube release assembly 19 is securely held to the upper end of the fuse tube 17. In order to i center the sleeve 151 on the fuse tube 17 a guide and stop pin 159 is employed which extends through the wall of the lower end section 152 and has a head 160 which extends into a recess 161that is located in'the extreme upper end of the fuse tube 17 as shown more clearly in FIG. 3A.

Immediately above the lower end section 152 is a cutaway section 162 in the sleeve 151 which exposes a substantial length of the upper tubular terminal 24. This construction permits the distal reverse curved ends 154- 154 of the C-shaped end sections 142142 for the latch contact spring 141 to have surface engagement over a substantial area with the juxtaposed portions of the upper tubular terminal 24. The construction is such that, when the dropout fuse 16 is latched in the closed position, the C-shaped end sections 142-142 are stressed so as to apply substantial contact pressure against the upper tubular terminal 24 with the result that a low electrical resistance path is provided therebetween. The general artube 169, as indicated by the broken line position in FIG.

is an upper end section 163 from which a latch hook 164,

formed integrally therewith, extends. The latch hook 164 has a latching shoulder 165 that is arranged to engage the non-fixed pivot roller 130 on the side opposite the short arm for the purpose of holding the dropout fuse 16 in the closed position. The latch hook 164 has an inclined latch engaging surface 166 for the purpose of lifting the latch 108 when the dropout fuse 16 is swung to the closed position. The arrangement is such that the forward lower end of the inclined surface 166 engages the forward end of the latch 108 and the lower edge of the transverse flange 124. As the closing movement continues the latch 108 is rotated about the pivot 109 against the biasing action of the spring 112. During the latter portion of the closingmovement the roller is engaged by the upper end of the inclined surface 166 and it is moved upwardly with a combined rotary and translatory movement since it is not held for rotation about a fixed pivot. Finally, the latching shoulder 164 moves underneath the roller 130 and is engaged thereby as the result of the downward movement of the latch 108 under the influence of gravity and the spring 112. The final latched position is effected with the roller 130 between the latching shoulder and the inner side 120 of the short arm 120. Since the roller 130 is held captive but has a limited degree of freedom of movement of both a rotary and translatory nature, no sliding or pivoting is required and, since no pivot is employed, pivot friction is completely eliminated. Moreover, it is unnecessary to provide a precisely aligned latch construction when the nonfixed pivot roller 130 is used in the manner outlined.

, In order to insure that the sleeve 151 is electrically connected to the upper terminal 24, a spring contact 167 is secured by a rivet 168 to the former as shown in FIG.

terminal 24 when an arc is drawn from the latch hook 164 on opening or closing of the dropout fuse 16.

The dropout fuse 16 is released to swing to the open position by lifting the latch 108 so that it rotates about the pivot 109. For this purpose a latch release tube 169 is slidably mounted within the upper end section 163 of the sleeve 151. It is telescoped over the upper end of the upper tubular terminal 24 that extends upwardly from the interior of the fuse tube 17. At its extreme lower end the latch release tube 169 has an integral radial flange 170 against which the lower end of a coil compression spring 171 reacts. The upper end of the spring 171 bears against the underside of a radial flange 172 that is formed integrally with the upper end section 163. The coil compression spring 171 functions to bias the latch release tube 169 to the lowermost or non-operated position. An annular seal 173 of suitable rubber-like material is located below the radial flange 170 at the lower end of the latch release tube 169. It provides a seal around the tubular terminal 24 to prevent the entrance of extraneous material such as water and insects and the like into the interior of the latch release tube 169 and into the space occuplied by the spring 171 where the sliding movement of the latch release tube 169 might be interfered with. The upper end is sealed by a sealing gasket 174 that is engaged by a latch release ring 175which is secured in a suitable manner to the latch release tube 169 so that it moves therewith.

When the dropout fuse 16 is in the closed position on the mounting 10 and the fusible element 140 is intact, the

latch release ring 175 underlies the distal end 176 of the latch 108. On upward movement of the latch release 11, there is a corresponding upward movement of the latch release ring 175. This is accompanied by upward movement of the distal end 176 of the latch 109 which is of a sufficient ,extent to cause the roller 130 to roll upwardly along the latching shoulder 165 and at the same release tube 169 is not cocked in the upper end section 163 of the sleeve 151 and prevented from moving upwardly to the released position. The guide ring 177 is preferably formed of insulating material, such as nylon, to avoid likelihood of-corrosion and to minimize friction between the tubular terminal 24 and the release tube 169. A release tube cap 178 closes the upper end of the latch release tube 179 the upper end of which, as indicated at 179, is turned over to hold the cap 178 in position.

In order to permit manual operation of the fuse tube release assembly 19, a manually operable arm 181 is pivoted at 182 on a pin that extends transversely through the arms 183-183 that are cast integrally with'the sleeve 151. A nose portion 184 underlies the latch release ring 175 and, when the arm 181 is rotated in a clockwise direction on the pivot pin 182, the nose portion 184 engages the underside of the latch release ring 175 and moves it upwardly to the position shown by broken lines for lifting the latch 108 and moving the roller 130 out of latching engagemcnt with the latching shoulder 165. A two to one mechanical advantage is obtained during the unlatching operation since the roller 130 rolls upwardly along the latching shoulder 165 and relatively downwardly along the inner surface 120 of the short arm 120. A'hairpin spring 185 is employed for biasing the manually operable arm 181 to the non-operated position. The spring 185 at the ends 186 bears against the under sides of the aims 183183. It is looped over the pivot pin '182 on opposite sides of the arm 181 and'the central portion bears against a shoulder 187. Ah eye section 188, formed integrally with the manually operable arm 181, is provided for receiving a prong of a switch stick. The eye section 188 is employed either for manually unlatching the fuse tube release assembly 19 from the latch assembly 15 or it is employed, when the dropout fuse 16 is being moved to the closedposition, to facilitate such action.

blow it will be apparent that, when the dropout fuse 16 is in the closed position on the mounting 10. current will flow from the line conductor clamped to the hinge terminal pad '70 through hinge contact spring 73, trunnion contact plate 88, lower terminal or ferrule 22, inner metallic sleeve 46, bridge 44, terminal rod 41, fusible element 40, rod-like-terminal 29, contact section 39, contact fingers 37, contact sleeve 36, upper tubular terminal 24, latch contact spring 141, reinforcing spring 145 to latch terminal pad 138 and thence to the line conductor clamped thereto.

When the fusible element '40 blows, the' rod-like terminal 29 is no longer restrained. It moves upwardly under the influence of the coil compression spring 32 to draw and extend the are into the bore 51 where it is extinguished. The continued upward movement of the rodlike terminal 29 carries with it the latch trip pin 28. It projects through the opening '27 in the washer 26 at the upper end of the upper tubular terminal 24 and engages the under side of the'release tube cap 178. This lifts the latch release tube 169 to the alternate position shown by broken lines and carries with it the latch release ring 155. As described hercinbefore, the upward movement of the latch release ring 175 carries with it the distal end 176 of the latch 108. It rotates in a counterclockwise direction about the pivot 109 and the roller 130 finally is moved out of latching engagement with the latching shoulder 165 with the twoto one mechanical advantage as previously described. The dropout fuse 16 then swings downwardly on the trunnions 85-85 to the open position where it engages the rubber bumper 67 which cushions the opening movement and reduces the shock incident to such action.

The operator then inserts the prong of a switch stick in the eye section 87 which now extends above the hinge assembly 14 with the arcuate shoulders 86--86 out of alignment with the arcuate flanges 6464. Consequently the blown dropout fuse 16 can be lifted out of the slots 63-453 and lowered to the ground. Then the trunnion assembly 18 and fuse tube release assembly 19 are removed from the blown fuse and applied to an unblown fuse. When the assembly is completed, the unblown dropout fuse 16 is replaced in the slots 63-63 through the use of the eye section 87. Thereafter, when the dropout fuse 16 is hanging downwardly by the trunnions 85--85, the prong of the switch stick is inserted in the eye section 188 whereupon the assembly can be swung upwardly to the fully closed and latched position. The dropout fuse 16 can be slammed to this position by a lineman on a pole or from the ground. Since the latch 108 is formed of relatively light weight material, aluminum or engagement with the latching shoulder '165 as the fuse'16 is swung to the closed position.

As pointed out above the current path extends from the hinge terminal pad 70 through the hinge contact spring 73 and trunnion contact plate to the lower terminal or ferrule 22 of the fuse 16. At the upper end no current flows through the hinge base 58 and trunnion 5 assembly 18, except for the trunnion contact plate 88 of the latter. Likewise no current flows through latch base 102 and fuse tube release assembly 19. Since these parts are not required to conduct current, they can be formed wholly or in part of insulating material such as plastic material having the requisite strength and weather resisting characteristics. For example reinforced plastic material such as fiber glass can be molded to conform essentially to the size and shape of the aluminum or magnesium parts. materials are employed to overcome the capacity effect between the terminal pads 70 and 138 and the respective metallic end caps 12' and 13' on the lower and upper insulators 12 and 13, they are interconnecting by conducting material such as the high resistance conducting material 77 applied to the insulating plate 77. When the hinge base 58 is formed of insulating material, it is unnecessary to provide this insulating plate 77.

What is claimed as new is: 1. A dropout fuse construction comprising, in combination:-

(a) upper and lower support bases, (b) means'mounting said support bases in insulated spaced relation, -(c) a dropout fuse tube interconnected by a fusible element that restrains a latch release member, (d) means rotatably mounting the lower end fuse tube on said lower support base, i (e) means releasably latching the upper end of said fuse tube to said upper support base and arranged and adapted on blowing of said fusible element to be unlatched by said latch release member including:

(1) a latch pivotally mounted on said upper support base, 5 (2) means biasing said latch downwardly to latching position,

of said When insulating instead of conducting having terminals at its ends (3) a latch hook extending laterally from the upcaptive with a limited degree of freedom for translatory movement.

5. The invention, as set forth in claim 2, wherein a non-fixed pivot, roller is mounted on the latch for latching engagement by the latch book.

6. In combination:

(a) a fuse tube,

(b) a ferrule of relatively good electrical conductivity secured to one end of said fuse tube,

(c) a tubular section of relatively poor electrical conductivity telescoped over said ferrule,

2. In a dropout fuse construction, in combination: (d) a trunnion section integral with said tubular see- (a) a metallic'hinge base carrying: tion and having trunnions extending laterally there- (1) ahinge terminal pad, from for pivotally mounting said fuse tube, (2) ahinge contact spring, and (e) means for electrically bypassing said tubular sec- (3) means clamping said hinge contact spring in tion and said trunnion section comprising'a contact circuit with said hinge terminal pad and both to plate of relatively good electrical conductivity movsaid hinge base; ably mounted on said trunnion section for contact (b) a metallic latch base carrying: engagement with said ferrule, and

(l) a latch terminal pad, (f) means on said trunnion section for clamping said (2) a latch contact spring, contact plate in contact engagement at one end with (3) means clamping said latch contact spring in said ferrule.

circuit with said latch terminal pad and both to said latch base, and (4) a pivoted latch biased downwardly; (c) means mounting said latch base in insulated spaced relation above said hinge base; (d) a fuse tube having:

(1 a grooved ferrule at its lower end,

7. The invention, as set forth in claim 6, wherein the clamping means includes:

(a) a flange depending from the clamping plate, and

(b) a bolt threaded on the trunnion section engaging said flange for moving said contact plate into clamping engagement with the ferrule.

8. Means for latching a fuse tube having a laterally ex- (2) a tubular terminal extending out of its upper end engaging said latch contact spring under substantial contact pressure,

tending latch hook in circuit closed position and making electrical contact with a terminal thereof comprising, in combination:

(3) fusible means interconnecting said ferrule and said tubularterminal, and

(4) a latch trip pin restrained by said fusible means and biased for movement out of the up- (a) a metallic latch base, I

(b) a terminal pad separate and distinct from said latch base,

(c) a contact spring,

per d of id b l t i l on bl i f (d) means clamping said contact spring in circuit with said fusible means; said terminal pad and both to said latch base, (e) a trunnion assembly rotatably mounted on said I la c pi ed on said latch base,

hinge base carrying: (f) a non-fixed pivot roller having trunnions at its (1) a tubular section telescoped over said ferrule, ends on Said latch for latching engagement with said (2) a trunnion contact plate movable transversely latch o and of said fuse tube, and (g) means on said latch defining slots at the ends of (3) means holding one end of said trunnion onsaid roller in which said trunnions are held captive tactv plate in contact engagement with said fer- With ailimited degree of freedom for translator) rule at the bottom of the groove therein, movement (4) the opposite end of said contact plate engag- 9 In a dropout fuse construction, in combination:

ing said hinge contact spring under substantial an aluminum hinge base carrying? contact pressure; and a hinge terminal pad, (f) a fuse tube release assembly including: ahinge colltactspfingiand (l) a sleeve telescoped over said tubular terminal, means Clamping Said hinge Contact Spring in clamped to the upper end of said fuse tube, circuit with said hinge terminal pad and both to having a cutaway section through which said Said i ge base; latch contact spring extends into contact enan alumifiumlatch base carrying! gagement with said tubular terminal, fllaichterminalpad, (2) a latch hook extending laterally into latching a latch contact spring,

engagement with said pivoted latch, and means clamping said latch Contact Spring in (3) a slidably mounted release tube for engaging circuit with said latch terminal pad and both to said latch and adapted to be moved longitudisaid latch base, and nally by said latch trip pin on blowing of said a pivoted latch biased downwardly; fusible element to rock said latch out of en- (0) means mounting said latch base in insulated spaced gagement with said latch hook and thereby perrelation above said hinge base, and f Sald fuse tube to f f downwardly on said (d) insulation between said hingebase and said hinge h g P P terminal pad providing a relatively high resistance T e f asset forth m clalm, Wherem: conducting path therebetween to prevent flow of (a) the hinge base, latch base, trunnion assembly and normal load current 111 h m fuse tube release assembly are formed of metal havw l e -avmg Su merit current ing relatively high electrical surface resistance, and cfirrymg capability to nuulfy the capac'ty cfiect (b) the hinge terminal pad, hinge contact spring, latch t terminal pad, latch contact spring, and trunnion con- D mp out fuse mounmg means compnsmg tact plate are formed of relatively low electrical rebmauon: sistance metaL (a) upper and lower aluminum support bases, The invention, as Set f th in claim 3, wherein: (b) means mounting said support bases in insulated (a) the metal having relatively high electrical surface Spaced relation, I

re istan e i ea t aluminum, and (c) a dropout fuse tube having terminals at its ends I (b) the low electrical resistance metal includ a b interconnected by a fusible element that restrains a stantial amount of copper. latch release member,

thereon having sufiicient current carrying capability to nullify the capacity effect provided thereby.

References Cited by the Examiner UNITED STATES PATENTS 2,212,632 8/1940 Bodendieck 200-414 2,578,255 12/1951 Lindell 200-1 14 14 2,599,186 6/1952 Lindell 200'114 2,750,469 6/1956 Baker 200-114 2,854,074 9/1958 Frank et a1. 200-166 References Cited by the Applicant UNITED STATES PATENTS 2,179,759 11/ 1939 Schultz. 2,212,632 8/1940 Bodendieck. 2,269,130 1/ 1942 Schultz. 2,328,745 9/1943 Sandin. 2,599,186 6/1952 Lindell. 2,910,560 10/1959 Stroup et a1.

OTHER REFERENCES ITE Bulletin 1,240-2A, February 1961.

BERNARD A. GILHEANY, Primary Examiner. ROBERT K. SCHAEFER, Examiner.

2 H. A. LEWITTER, Assistant Examiner. 

1. A DROPOUT FUSE CONSTRUCTION COMPRISING, IN COMBINATION: (A) UPPER AND LOWER SUPPORT BASES, (B) MEANS MOUNTING SAID SUPPORT BASES IN INSULATED SPACED RELATION; (C) A DROPOUT FUSE TUBE HAVING TERMINALS AT THE ENDS INTERCONNECTED BY A FUSIBLE ELEMENT THAT RESTRAINS A LATCH RELEASE MEMBER, (D) MEANS ROTATABLY MOUNTING THE LOWER END OF SAID FUSE TUBE ON SAID LOWER SUPPORT BASE, (E) MEANS RELEASABLY LATCHING THE UPPER END OF SAID FUSE TUBE TO SAID UPPER SUPPORT BASE AND ARRANGED AND ADAPTED ON BLOWING OF SAID FUSIBLE ELEMENT TO BE UNLATCHED BY SAID LATCH RELEASE MEMBER INCLUDING: (1) A LATCH PIVOTALLY MOUNTED ON SAID UPPER SUPPORT BASE, (2) MEANS BIASING SAID LATCH DOWNWARDLY TO LATCHING POSITION, (3) A LATCH HOOK EXTENDING LATERALLY FROM THE UPPER END OF SAID FUSE TUBE, (4) A NON-FIXED PIVOT ROLLER HAVING TRUNNIONS AT ITS ENDS ON SAID LATCH FOR LATCHING ENGAGEMENT WITH SAID LATCH HOOK, AND (5) MEANS ON SAID LATCH DEFINING SLOTS AT THE ENDS OF SAID ROLLER IN WHICH SAID TRUNNIONS ARE HELD CAPTIVE WITH A LIMITED DEGREE OF FREEDOM FOR TRANSLATORY MOVEMENT. 